Field of the Invention
The present invention relates to power-protection apparatuses of motors, and in particular to power-protection apparatuses that save energy.
Description of the Related Art
The prior art provides various circuit-protection methods to prevent the expensive and delicate motors from damage.
The prior art provides three methods for over-voltage protection: method I—improving circuit-element specifications; method II—protecting circuits by using a transient voltage suppressor (TVS); and method III—protecting circuits by using an operational amplifier (OP).
For method I, improving circuit-element specifications means raising the cost, and less choice for the circuit elements. Therefore, method I applies only to simple circuits and is rarely employed. For method II, although using TVS is the mainstream approach, this method is only suitable for eliminating transient high voltage or surges with low power, such as ESD, and circuits may break when the high voltage is sustained. For method III, the OP not only has a higher cost and limited input voltage, but also has complicated circuit design and a slower circuit-reaction speed.